LNode TentativeExpr(VList<LNode> attrs, out TentativeResult result, bool allowUnassigned = false)
{
result = new TentativeResult(InputPosition);
var oldState = _tentative;
_tentative = new TentativeState(true);
{
try {
bool failed = false;
result.Result = Expr(StartExpr).PlusAttrs(attrs);
if ((LA0 != EOF && LA0 != TT.Semicolon && LA0 != TT.Comma)) {
failed = true;
}
result.Errors = _tentative.DeferredErrors;
result.InputPosition = InputPosition;
if (failed || _tentative.LocalErrorCount != 0) {
InputPosition = result.OldPosition;
return null;
}
} finally {
_tentative = oldState;
}
}
return Apply(result);
}
LNode Apply(TentativeResult result)
{
InputPosition = result.InputPosition;
if (result.Errors != null) {
result.Errors.WriteListTo(CurrentSink(false));
}
return result.Result;
}
// Parses an expression (TentativeExpr) or variable declaration (TentativeVarDecl).
// Returns the parsed node on success or null if outer-level parse error(s)
// occurred; the out param result is never null, and in case of success it
// is the same as the return value. Error handling is tricky... we fail if
// there are errors at the current level, not if there are errors in
// parenthesized subexpressions.
LNode TentativeVarDecl(VList<LNode> attrs, out TentativeResult result, bool allowUnassigned = false)
{
result = new TentativeResult(InputPosition);
var oldState = _tentative;
_tentative = new TentativeState(true);
{
try {
bool failed = false;
int _;
var cat = DetectStatementCategoryAndAddWordAttributes(out _, ref attrs, DetectionMode.Expr);
if ((cat != StmtCat.MethodOrPropOrVar)) {
failed = true;
result.Result = F.Missing;
} else {
bool hasInitializer;
result.Result = VarDeclExpr(out hasInitializer, attrs);
if ((!hasInitializer && !allowUnassigned)) {
Error(-1, "An unassigned variable declaration is not allowed in this context");
}
}
result.Errors = _tentative.DeferredErrors;
result.InputPosition = InputPosition;
if (failed || _tentative.LocalErrorCount != 0) {
// error(s) occurred.
InputPosition = result.OldPosition;
return null;
}
} finally {
_tentative = oldState;
}
}
return Apply(result); // must Apply after finally block
}
